1. Field of the Invention
The present inventive concept relates to an organic light emitting diode, and more particularly, to an organic light emitting diode.
2. Description of the Related Art
Light emitting diodes are self-emission devices that have wide viewing angles, high contrast ratios, and short response time
Light emitting diodes can be categorized into inorganic light omitting diodes and organic light emitting diodes (OLEDs) according to an emitting layer forming material. OLEDs are better than inorganic light emitting diodes in terms of luminosity, driving voltage, and response speed. In addition, OLEDs can generate natural colors.
In general, an OLED includes a substrate, an anode disposed on the substrate, and a hole transport layer, an emitting layer, an electron transport layer and a cathode which are sequentially disposed on the anode. The hole transport layer, the emitting layer, and the electron transport layer are organic thin films.
An exemplary driving principle of the organic light emitting diode is as follows.
When a voltage is applied between the anode and the cathode, holes injected through the anode move to the emitting layer through the hole transport layer and electrons injected through the cathode move to the emitting layer through the electron transport layer. Carriers, such as holes and electrons, are re-combined in the emitting layer to form excitons. The excitons are changed from an excited state to a ground state and thus, fluorescent molecules in the emitting layer are excited, thereby emitting light.
However, conventional OLEDs have undesirable driving voltage, luminosity, current density, power efficiency, and lifetime characteristics. Accordingly, there is a need to improve these characteristics of OLEDs.